Enhanced DC-DC converter, method for operating the DC-DC converter, environmental energy-harvesting system comprising the DC-DC converter, and apparatus comprising the energy-harvesting system

Patent metadata

Field	Value
Publication number	US-9450489-B2
Application number	US-201414181063-A
Country	US
Kind code	B2
Filing date	Feb 14, 2014
Priority date	Feb 21, 2013
Publication date	Sep 20, 2016
Grant date	Sep 20, 2016

Abstract

A DC-DC converter independently supplies electrical loads. For each load, an output load signal is compared to a reference to generate a result indicating a need to supply the respective electrical load. A first detection is made as to whether a first electrical load needs to be supplied and a second detection is made as to whether any remaining electrical loads need to be supplied. The first electrical load is supplied if the first detection is positive and the second detection is negative.

First claim

What is claimed is:

1. A DC-DC converter, comprising:
a charge switch and a discharge switch connected in series at a common node;
an inductor having a first conduction terminal coupled to the common node;
a plurality of coupling switches, each coupling switch coupled between a second conduction terminal of the inductor and a respective electrical load output node to supply an output supply signal;
a plurality of comparator circuits, each comparator circuit configured to receive a respective output supply signal and a respective comparison reference signal, and each comparator circuit configured to generate a respective comparison result signal indicative of a need to supply the respective electrical load output node;
a control logic circuit operable in response to a first operating time interval and an immediately subsequent second operating time interval and configured to:
(a) detect in a first verification instant preceding the first operating time interval whether, on a basis of the respective result signal, a first electrical output node needs to be supplied;
(b) detect, in a second verification instant immediately subsequent to the first operating time interval but preceding the second operating time interval, whether, on the basis of the respective result signal, any other electrical output nodes need to be supplied; and
(c) supply said first electrical output node during the first and second operating time intervals in a case where (a) yields a positive outcome and (b) yields a negative outcome.

2. The converter according to claim 1 , wherein the control logic circuit is further configured to supply said first electrical output node during the first operating time interval and supply a one of the other electrical output nodes during the second operating time interval in the case where (a) yields the positive outcome and (b) indicates that said other electrical output node needs to be supplied.

3. The converter according to claim 2 , wherein the first operating time interval includes a first time portion in which the inductor is charged and a second time portion in which the inductor is discharged, and wherein the second operating time interval includes a first time portion in which the inductor is charged and a second time portion in which the inductor is discharged.

4. The converter according to claim 3 , further comprising:
an adaptive-control circuit configured to acquire for each electrical output node, a signal indicating a voltage value stored across the inductor, and generate the respective first time portion of the first and second operating time intervals having a duration that is a function of the signal indicating the voltage value detected,
wherein, during the respective first time portion of the first and second operating time intervals, the charge switch is controlled so as to connect the first conduction terminal of the inductor to a source of electrical energy in order to charge the inductor, and wherein, during the respective second time portions of the first and second operating time intervals, the discharge switch is controlled so as to connect the first conduction terminal of the inductor to a reference terminal for discharging the inductor.

5. The converter according to claim 4 , wherein the adaptive-control circuit comprises an operational circuit including: a first input terminal coupled to the source of electrical energy to receive an input supply signal; a second input terminal coupled to one of the electrical output nodes to receive the respective output supply signal; and an output terminal configured to supply an intermediate signal proportional to a difference between the input supply signal and the output supply signal, the respective first time portions of the first and second operating time intervals being inversely proportional to said intermediate signal.

6. The converter according to claim 1 , further comprising:
a current-detector circuit coupled to the first conduction terminal of the inductor and configured to generate a discharge-current signal indicative of a comparison of an electrical signal present on the first conduction terminal and a reference signal; and
a discharge-driving circuit responsive to the discharge-current signal to detect, during the second time portion of the first operating time interval, a zero-current state in which a discharge current through the discharge switch and the inductor assumes a value close to a zero value, and, in response to such detection of the zero-current state open the discharge switch,
the control logic circuit further configured to terminate the first operating time interval upon detection of the zero-current state.

7. The converter according to claim 6 , wherein the current-detector circuit includes:
a pre-amplifier of a variable-gain type coupled to the first conduction terminal of the inductor and coupled to a reference terminal and configured to generate an amplified signal indicating a value of current that flows through the discharge switch and the inductor; and
a comparator configured to generate the discharge-current signal in response to a comparison of the amplified signal to the reference signal,
wherein the control logic circuit is configured to vary a gain of the pre-amplifier such that a slope of the amplified signal is independent of a duration of the second time portions of the first and second operating time intervals.

8. The converter according to claim 6 , further comprising an anti-oscillation switch connected in parallel with the inductor, the discharge-driving circuit configured to close the anti-oscillation switch when the discharge current through the discharge switch reaches said value close to the zero value.

9. The converter according to claim 1 , further comprising a circuit configured to generate dead times including a guard time interval between the first operating time interval and the second operating time interval.

10. The converter according to claim 9 , wherein the circuit configured to generate dead times comprises:
a conduction-control logic configured to generate a first charge-control signal to control the charge switch in a first operating state and, alternatively, in a second operating state, and to generate a first discharge-control signal to control the discharge switch in the first operating state when the charge switch is in the second operating state, and vice versa;
a first delay element configured to acquire a second charge-control signal as a function of the first charge-control signal and apply a delay having a value equal to the guard time interval to generate a delayed charge-control signal;
a second delay element configured to acquire a second discharge-control signal as a function of the first discharge-control signal and apply the delay having the value equal to the guard time interval to generate a delayed discharge-control signal,
the conduction-control logic further configured to acquire the delayed charge-control signal and the delayed discharge-control signal, detect a variation from the first operating state to the second operating state of one between the charge switch and the discharge switch, and generate a corresponding variation from the second operating state to the first operating state of the other between the charge switch and the discharge switch.

11. The converter according to claim 1 , further comprising a first circuit configured to drive the charge switch comprising:
a driving device including a plurality of inverters connected in series to one another;

a bootstrap capacitor coupled to a first supply input and to a second supply input of the driving device to supply the driving device;
a bootstrap switch con

Assignees

• St Microelectronics Srl

Inventors

• Gasparini Alessandro
• Miluzzi Eugenio
• Cattani Alberto
• Ramorini Stefano

Classifications

• H02M3/158 Primary

  including plural semiconductor devices as final control devices for a single load · CPC title

• H02M3/33561

  having more than one ouput with independent control · CPC title

• H02M3/1584

  with a plurality of power processing stages connected in parallel · CPC title

• H02M2001/009

  Electricity · mapped topic

• H02M2001/0087

  Electricity · mapped topic